Question 97 - Two viruses a and b with masses of Ma and Mb are moving at velocities of Va and Vb respectively, facing towards each other and collide. After collision both masses of Ma and Mb disappear. (a) Find the total momentum available for both a and b. Hint : momentum = mass x velocity = M x V. (b) Guess the total energy E generated from the disappearance of a and b. Let c to be the velocity of light. Hint : E is equal to M c square.

Question 98 - The Planck-Einstein relation connects the particulate photon energy E with its associated wave frequency f to produce E = hf. Let h to be the Planck constant. The frequency f, wavelength L and speed of light c are related by E = hc / L. With p denoting the linear momentum of a particle, the de Broglie wavelength L of the particle is given by L = h / p. (a) Find the equation of E as a function of p and c. (b) If E has a unit of electron-volt and f has a unit of 1 / second, then what is the unit of h?

Question 96 - In infrared spectrum, one of the factors affecting peak location is the mass of the atoms. The stretching frequency of a bond connected to a lighter atom will be greater than the same bond connected to a heavier atom. (a) For halogens like florine (F), chlorine (Cl), bromine (Br), iodine (I) and astatine (At), what is their IUPAC group number? Hint : The proton numbers for F, Cl, Br, I and At are 9, 17, 35, 53 and 85 respectively. (b) For the compounds of H-F, H-Cl, H-Br, H-I and H-At, which one has the lowest stretching frequency and which one has the highest stretching frequency? State the reasons.